Transcranial Doppler with contrast injection for the detection of patent foramen ovale in stroke patients.

Right-to-left shunt through a patent foramen ovale was searched for in 80 patients with acute ischemic stroke by simultaneously performing transthoracic two-dimensional echocardiography and transcranial Doppler during agitated saline injection. A patent foramen ovale was detected by echocardiography in 14 patients (17.5%). Transcranial Doppler correctly identified all 14 patients, and 7 more patients in whom echocardiographic findings were indeterminate. Prevalence of patent foramen ovale by transcranial Doppler was therefore 26.3% (21 of 80 patients). Concordance between the two tests was 91.3% (73 of 80 patients). The delivery of contrast material to cerebral vessels is therefore demonstrable by transcranial Doppler in all patients diagnosed by contrast echocardiography, suggesting that paradoxical embolization through a patent foramen ovale may be more frequent than previously thought. Transcranial Doppler with contrast injection is a valid alternative in case of poor echocardiographic image quality.